From prior studies, it would appear that some patients with chromosome anomalies, particularly those which involve extra chromosomes in some or all cells, have an increased susceptibility to cellular transformation by oncogenic agents and an increased risk of malignancy. The purpose of this project has been to study systematically from both a clinical and laboratory approach individuals with various disorders including patients and relatives of patients with chromosome abnormalities, patients with a known increased risk of malignancy, and patients with established malignant disorders before and after treatment with antineoplastic agents. These groups will have SV40 transformation studies performed and ancillary tests as indicated.